ACID RAINACID RAINCE 326 Principles of Environmental CE 326 Principles of Environmental Engineering Engineering Prof. Tim EllisProf. Tim EllisJanuary 22, 2007January 22, 2007What is acid rain?What is acid rain?zzMore accurate term may More accurate term may be acid depositionbe acid depositionzzOccurs in two formsOccurs in two formszzwet deposition (acidic wet deposition (acidic rain, fog, and snow)rain, fog, and snow)zzdry deposition (acidic dry deposition (acidic gases and particles)gases and particles)zzPrincipal components Principal components are SOare SOXXand NOand NOXXzzAbout 2/3 of SOAbout 2/3 of SOXXand and 1/4 of NO1/4 of NOXXcomes from comes from power plants (most are power plants (most are coal burning)coal burning)CE 326 Principles of Environmental Engineering, Copyright © 2007 Tim Ellis, Iowa State UniversityHow do we measure?How do we measure?zzpH of pH of ““naturalnatural””rain water is 5.6 (pKrain water is 5.6 (pKa1a1of carbonic of carbonic acid is 6.35)acid is 6.35)zzare monitored by two networks, both supported are monitored by two networks, both supported by EPAby EPAzzThe National Atmospheric Deposition Program The National Atmospheric Deposition Program measures wet deposition, and its Web site measures wet deposition, and its Web site (http://(http://nadp.sws.uiuc.edunadp.sws.uiuc.edu/) features maps of rainfall /) features maps of rainfall pHpHzzThe Clean Air Status and Trends Network The Clean Air Status and Trends Network (CASTNET) measures dry deposition. Its features (CASTNET) measures dry deposition. Its features information about the data it collects, the measuring information about the data it collects, the measuring sites, and the kinds of equipment it uses sites, and the kinds of equipment it uses --http://http://www.epa.gov/castnetwww.epa.gov/castnet/ / CE 326 Principles of Environmental Engineering, Copyright © 2007 Tim Ellis, Iowa State UniversityEffects of acid rainEffects of acid rainzzdamage to forests and soils, fish and other living damage to forests and soils, fish and other living things, materials, and human health.things, materials, and human health.zzacidification of lakes and streams acidification of lakes and streams zzIn a National Surface Water Survey (NSWS)In a National Surface Water Survey (NSWS)zzeffects of acidic deposition in over 1,000 lakes larger effects of acidic deposition in over 1,000 lakes larger than 10 acres and in thousands of miles of streams than 10 acres and in thousands of miles of streams believed to be sensitive to acidification was studied. believed to be sensitive to acidification was studied. zzacid rain caused acidity in 75 percent of the acidic acid rain caused acidity in 75 percent of the acidic lakes lakes zzacid rain caused acidity in about 50 percent of the acid rain caused acidity in about 50 percent of the acidic streamsacidic streamsCE 326 Principles of Environmental Engineering, Copyright © 2007 Tim Ellis, Iowa State UniversityEffects of acid rainEffects of acid rainzzregions in the U.S. identified as containing many of the regions in the U.S. identified as containing many of the surface waters sensitive to acidification include:surface waters sensitive to acidification include:zzthe Adirondacks and Catskill Mountains in New York state, the Adirondacks and Catskill Mountains in New York state, zzthe midthe mid--Appalachian highlands along the east coast, Appalachian highlands along the east coast, zzthe upper Midwest, and mountainous areas of the Western the upper Midwest, and mountainous areas of the Western United States. United States. zzIn areas like the Northeastern United States, where soil bufferiIn areas like the Northeastern United States, where soil buffering ng capacity is poor, some lakes now have a pH value of less than 5.capacity is poor, some lakes now have a pH value of less than 5.zzOne of the most acidic lakes reported is Little Echo Pond in One of the most acidic lakes reported is Little Echo Pond in Franklin, New York. Little Echo Pond has a pH of 4.2.Franklin, New York. Little Echo Pond has a pH of 4.2.zzalso a problem in lakes smaller than 10 acres that were not also a problem in lakes smaller than 10 acres that were not included in the NSWS (may increase the number up to fourincluded in the NSWS (may increase the number up to four--fold).fold).CE 326 Principles of Environmental Engineering, Copyright © 2007 Tim Ellis, Iowa State UniversityEffcetsEffcetsof acid rainof acid rainzzapproximately 70 percent of sensitive lakes in the approximately 70 percent of sensitive lakes in the Adirondacks are at risk of episodic acidification (brief Adirondacks are at risk of episodic acidification (brief periods of low pH)periods of low pH)zzlow buffered streams: low buffered streams: zz580 of the streams in the Mid580 of the streams in the Mid--Atlantic Coastal Plain are acidic, Atlantic Coastal Plain are acidic, zzin the New Jersey Pine Barrens, over 90 percent of the streams in the New Jersey Pine Barrens, over 90 percent of the streams are acidic (highest rate of acidic streams in the nation), and are acidic (highest rate of acidic streams in the nation), and zzover 1,350 of the streams in the Midover 1,350 of the streams in the Mid--Atlantic Highlands (midAtlantic Highlands (mid--Appalachia) are acidic, primarily due to acidic deposition.Appalachia) are acidic, primarily due to acidic deposition.zzCanadian government has estimated that 14,000 lakes Canadian government has estimated that 14,000 lakes in eastern Canada are acidic.in eastern Canada are acidic.CE 326 Principles of Environmental Engineering, Copyright © 2007 Tim Ellis, Iowa State UniversityAffects Fish and Aquatic SpeciesAffects Fish and Aquatic Specieszzacid rain causes a cascade of effects that harm acid rain causes a cascade of effects that harm or kill individual fish, reduce fish population or kill individual fish, reduce fish population numbers, completely eliminate fish species from numbers, completely eliminate fish species from a a waterbodywaterbody, and decrease biodiversity., and decrease biodiversity.zzincreased aluminum levels cause chronic stress increased aluminum levels cause chronic stress that may not kill individual fish, but leads to lower that may not kill individual fish, but leads to lower body weight and smaller size and makes fish body weight and smaller size and makes fish less able to compete for food and habitat.less able to compete for food and habitat.zzgenerally, the